[yoshisushi]

One reason I can imagine that Line Level is better is because it's simpler to hook up (just a pair of RCA cables), but other than that is one better than the other?

I ask because I'm thinking of getting a 4 channel amp that has both. If I can use the High Level imputs for this specific project I'm going to be miles ahead.

[AudioGuru]

Line level is better for a few reasons.

High level signals have already been through your deck's amplifier. Basically you are reducing an amplified signal to be amplified again. Any poor audio characteristics of the deck amplifier are going to be present in your external amplifier.

Additionally, when using the high level inputs on an amplifier, you are employing another circuit to handle that signal. Anytime you put a signal through an electronic circuit of any type, you are increasing the noise and decreasing the quality. Keeping that number to a minimum maintains your signal quality.

Line level RCA cables(good ones) are usually shielded, unlike speaker wires. You have a better chance of getting a clean signal into your amplifier. RFI and EMI degradation is less likely with a good shielded interconnect. Remember, amplifiers are stupid; they'll amplify noise right as well as signal.

[yoshisushi]

The head unit I have only has one pre-amp output and the 4 channel amp requires two RCA imputs, one for Front and one for Rear.

Is buying a new head unit with two outputs the best/only way to avoid using the high level inputs?

[AudioGuru]

Some 4 channel amps allow you to gather the input for all 4 channels from 2 inputs, but most don't. Run one set of RCA cables back from your deck and use 2 RCA Y-Splitters to utilize all 4 inputs. (1 Female to 2 Male).

Monster Y Splitter

[yoshisushi]

Thanks so much for the help....

Does line level have digital info that has all the channels going across one cable? I ask because I'm just wondering if I'll still have Left/Right and Front/Back fade from the head unit using just one RCA output. I really didn't think about any of this when I bought it.

Here are pics of the amp i'm looking at....


~~ and the other end ~~

[AudioGuru]

After looking at your amplifier I can say the following things:

1) You will retain balance control at the deck, however you will lose fader control. Your fade will be set by adjusting your gains(input level) on the amplifier.

2) The Y-splitters I posted earlier will not work since the inputs are too far apart for it to stretch. You'll need a 1 male to 2 female Y splitter and then a very short set of RCAs to jump over to the other input. The male end will plug into the front input, one female end will plug into your RCA coming from the deck. The other female will plug into the short RCA to jump to the rear input.

OR

3) You could run the right RCA to the front input and use a 1F 2M splitter there and run the left RCA to the rear input and use a 1F 2M splitter there as well. Hook your front speakers to both left outputs and rear speakers to both right outputs. This will require a little more time to set your crossovers and gains equally for front & rear(now left & right), but will save you $ on wiring. Remember, amps are stupid, you make them do whatever you want.(disclaimer: this will only work if you are not hooking subs to this amplifier, just peripheral speakers)